Among other things, coordinate measuring machines (“CMMs,” also known as surface scanning measuring machines) measure geometry and surface profiles, or verify the topography of known surfaces. For example, a CMM may measure the topological profile of a propeller to ensure that its surface is appropriately sized and shaped for its specified task (e.g., moving a 24-foot boat at pre-specified speeds through salt water).
To that end, conventional CMMs typically have a base directly connected with and supporting a movable assembly having a probe that directly contacts and moves along a surface of an object being measured. The base may also support the object being measured. Commonly, the base is formed from a material having a coefficient of thermal expansion that is different from that of the portion of the movable assembly it directly contacts. This disparity can cause the base to move relative to the assembly by microns, or even millimeters. With a change in the ambient thermal environment, this mismatch can significantly distort the geometry of the machine and skew the results of the measurement, particularly when measuring to the micron level.